refactor(engine): always connect buffered blocks on r/w hook finish (#4657)

crates/consensus/beacon/src/engine/hooks/controller.rs

@@ -1,10 +1,20 @@
-use crate::hooks::{EngineContext, EngineHook, EngineHookAction, EngineHookError, EngineHooks};
+use crate::hooks::{
+    EngineContext, EngineHook, EngineHookAction, EngineHookDBAccessLevel, EngineHookError,
+    EngineHookEvent, EngineHooks,
+};
 use std::{
     collections::VecDeque,
     task::{Context, Poll},
 };
 use tracing::debug;
 
+#[derive(Debug)]
+pub(crate) struct PolledHook {
+    pub(crate) event: EngineHookEvent,
+    pub(crate) action: Option<EngineHookAction>,
+    pub(crate) db_access_level: EngineHookDBAccessLevel,
+}
+
 /// Manages hooks under the control of the engine.
 ///
 /// This type polls the initialized hooks one by one, respecting the DB access level
@@ -41,28 +51,27 @@ impl EngineHooksController {
         &mut self,
         cx: &mut Context<'_>,
         args: EngineContext,
-    ) -> Poll<Result<EngineHookAction, EngineHookError>> {
+    ) -> Poll<Result<PolledHook, EngineHookError>> {
         let Some(mut hook) = self.running_hook_with_db_write.take() else { return Poll::Pending };
 
         match hook.poll(cx, args) {
             Poll::Ready((event, action)) => {
+                let result = PolledHook { event, action, db_access_level: hook.db_access_level() };
+
                 debug!(
                     target: "consensus::engine::hooks",
                     hook = hook.name(),
-                    ?action,
-                    ?event,
+                    ?result,
                     "Polled running hook with db write access"
                 );
 
-                if !event.is_finished() {
+                if !result.event.is_finished() {
                     self.running_hook_with_db_write = Some(hook);
                 } else {
                     self.hooks.push_back(hook);
                 }
 
-                if let Some(action) = action {
-                    return Poll::Ready(Ok(action))
-                }
+                return Poll::Ready(Ok(result))
             }
             Poll::Pending => {
                 self.running_hook_with_db_write = Some(hook);
@@ -89,7 +98,7 @@ impl EngineHooksController {
         cx: &mut Context<'_>,
         args: EngineContext,
         db_write_active: bool,
-    ) -> Poll<Result<EngineHookAction, EngineHookError>> {
+    ) -> Poll<Result<PolledHook, EngineHookError>> {
         let Some(mut hook) = self.hooks.pop_front() else { return Poll::Pending };
 
         // Hook with DB write access level is not allowed to run due to already running hook with DB
@@ -101,23 +110,22 @@ impl EngineHooksController {
         }
 
         if let Poll::Ready((event, action)) = hook.poll(cx, args) {
+            let result = PolledHook { event, action, db_access_level: hook.db_access_level() };
+
             debug!(
                 target: "consensus::engine::hooks",
                 hook = hook.name(),
-                ?action,
-                ?event,
+                ?result,
                 "Polled next hook"
             );
 
-            if event.is_started() && hook.db_access_level().is_read_write() {
+            if result.event.is_started() && result.db_access_level.is_read_write() {
                 self.running_hook_with_db_write = Some(hook);
             } else {
                 self.hooks.push_back(hook);
             }
 
-            if let Some(action) = action {
-                return Poll::Ready(Ok(action))
-            }
+            return Poll::Ready(Ok(result))
         } else {
             self.hooks.push_back(hook);
         }

crates/consensus/beacon/src/engine/hooks/mod.rs

@@ -6,7 +6,7 @@ use std::{
 };
 
 mod controller;
-pub(crate) use controller::EngineHooksController;
+pub(crate) use controller::{EngineHooksController, PolledHook};
 
 mod prune;
 pub use prune::PruneHook;
@@ -88,8 +88,6 @@ impl EngineHookEvent {
 pub enum EngineHookAction {
     /// Notify about a [SyncState] update.
     UpdateSyncState(SyncState),
-    /// Connect blocks buffered during the hook execution to canonical hashes.
-    ConnectBufferedBlocks,
 }
 
 /// An error returned by [hook][`EngineHook`].
@@ -107,6 +105,7 @@ pub enum EngineHookError {
 }
 
 /// Level of database access the hook needs for execution.
+#[derive(Debug, Copy, Clone)]
 pub enum EngineHookDBAccessLevel {
     /// Read-only database access.
     ReadOnly,

crates/consensus/beacon/src/engine/hooks/prune.rs

@@ -73,13 +73,7 @@ impl<DB: Database + 'static> PruneHook<DB> {
             }
         };
 
-        let action = if matches!(event, EngineHookEvent::Finished(Ok(_))) {
-            Some(EngineHookAction::ConnectBufferedBlocks)
-        } else {
-            None
-        };
-
-        Poll::Ready((event, action))
+        Poll::Ready((event, None))
     }
 
     /// This will try to spawn the pruner if it is idle:

crates/consensus/beacon/src/engine/mod.rs

@@ -39,7 +39,7 @@ use reth_tasks::TaskSpawner;
 use std::{
     pin::Pin,
     sync::Arc,
-    task::{ready, Context, Poll},
+    task::{Context, Poll},
     time::Instant,
 };
 use tokio::sync::{
@@ -69,7 +69,7 @@ mod handle;
 pub use handle::BeaconConsensusEngineHandle;
 
 mod forkchoice;
-use crate::hooks::EngineHooks;
+use crate::hooks::{EngineHooks, PolledHook};
 pub use forkchoice::ForkchoiceStatus;
 
 mod metrics;
@@ -1683,19 +1683,22 @@ where
         None
     }
 
-    fn on_hook_action(&self, action: EngineHookAction) -> Result<(), BeaconConsensusEngineError> {
+    fn on_hook_result(&self, result: PolledHook) -> Result<(), BeaconConsensusEngineError> {
+        if let Some(action) = result.action {
             match action {
                 EngineHookAction::UpdateSyncState(state) => {
                     self.sync_state_updater.update_sync_state(state)
                 }
-            // TODO(alexey): always connect buffered blocks if hook had the
-            //  `EngineHookDBAccessLevel::ReadWrite`
-            EngineHookAction::ConnectBufferedBlocks => {
-                if let Err(error) = self.blockchain.connect_buffered_blocks_to_canonical_hashes() {
-                    error!(target: "consensus::engine", ?error, "Error restoring blockchain tree state");
-                    return Err(error.into())
             }
         }
+
+        if result.event.is_finished() && result.db_access_level.is_read_write() {
+            // If the hook had read-write access to the database,
+            // it means that the engine may have accumulated some buffered blocks.
+            if let Err(error) = self.blockchain.connect_buffered_blocks_to_canonical_hashes() {
+                error!(target: "consensus::engine", ?error, "Error connecting buffered blocks to canonical hashes on hook result");
+                return Err(error.into())
+            }
         }
 
         Ok(())
@@ -1734,10 +1737,8 @@ where
             if let Poll::Ready(result) = this.hooks.poll_running_hook_with_db_write(
                 cx,
                 EngineContext { tip_block_number: this.blockchain.canonical_tip().number },
-            ) {
-                if let Err(err) = this.on_hook_action(result?) {
-                    return Poll::Ready(Err(err))
-                }
+            )? {
+                this.on_hook_result(result)?;
             }
 
             // Process all incoming messages from the CL, these can affect the state of the
@@ -1793,19 +1794,18 @@ where
             // 1. Engine and sync messages are fully drained (both pending)
             // 2. Latest FCU status is not INVALID
             if !this.forkchoice_state_tracker.is_latest_invalid() {
-                let action = ready!(this.hooks.poll_next_hook(
+                if let Poll::Ready(result) = this.hooks.poll_next_hook(
                     cx,
                     EngineContext { tip_block_number: this.blockchain.canonical_tip().number },
                     this.sync.is_pipeline_active(),
-                ))?;
-                if let Err(err) = this.on_hook_action(action) {
-                    return Poll::Ready(Err(err))
-                }
+                )? {
+                    this.on_hook_result(result)?;
 
-                // ensure we're polling until pending while also checking for new engine messages
-                // before polling the next hook
+                    // ensure we're polling until pending while also checking for new engine
+                    // messages before polling the next hook
                     continue 'main
                 }
+            }
 
             // incoming engine messages and sync events are drained, so we can yield back
             // control